Question

For the oxygen-balanced explosive ANFO reaction \[ 3NH_4NO_3 + CH_2 \rightarrow 7H_2O + CO_2 + 3N_2 \] the amount of ammonium nitrate (in kg, rounded off to two decimals) required for 100 L of fuel oil (density 850 kg/m$^3$) is __________.

Hint:

ANFO stoichiometry follows 3 moles of ammonium nitrate per mole of fuel (CH$_2$).

Answer 1

Correct Answer: 1453

Volume of fuel oil:
\[ V = 100\ \text{L} = 0.1\ \text{m}^3. \]
Mass of fuel oil:
\[ m_{fuel} = \rho V = 850 \times 0.1 = 85\ \text{kg}. \]
Molecular weight of fuel oil (CH$_2$):
\[ MW_{CH_2} = 14. \]
Moles of CH$_2$:
\[ n_{fuel} = \frac{85}{14} \approx 6.071. \]
Reaction stoichiometry: 1 mol CH$_2$ requires 3 mol NH$_4$NO$_3$.
Thus:
\[ n_{AN} = 3 \times 6.071 = 18.214\ \text{mol}. \]
Molecular weight of ammonium nitrate (NH$_4$NO$_3$):
\[ MW_{AN} = 80. \]
Mass required:
\[ m_{AN} = 18.214 \times 80 = 1457.1\ \text{kg}. \]
\[ \boxed{1457.10\ \text{kg}} \quad (\text{acceptable range: } 1453\text{–}1458) \]